1. Field of the Invention
The present invention relates to a fuel cell system comprising a fuel cell that generates electricity with a reaction between a fuel gas and an oxidant gas and an exhaust flow passage for a fuel exhaust gas of the fuel cell. The invention also relates to a method of operating the fuel cell system.
2. Background Information
Japanese Laid-Open Patent Publication No. 2008-270151 presents an example of a conventional fuel cell system comprising a fuel cell that generates electricity with a reaction between a fuel gas and an oxidant gas and an exhaust flow passage that guides a fuel exhaust gas discharged from the fuel cell to outside the system. In the fuel cell system presented in Japanese Laid-Open Patent Publication No. 2008-270151, a valve (purge valve) is provided in the exhaust flow passage to open and close the exhaust flow passage and a filter is provided in the valve to remove foreign particles.
With this type of fuel cell system, if water vapor or other form of moisture is contained in the fuel exhaust gas, then there is a likelihood that moisture will condense inside the exhaust flow passage and water will collect. Water adheres particularly readily to the mesh of the filter. Consequently, when the system is stopped and allowed to sit in a low-temperature environment, there is a possibility that water adhered to the filter will freeze and block the exhaust flow passage.
Therefore, the fuel cell system of Japanese Laid-Open Patent Publication No. 2008-270151 is provided with a heater configured to heat the filter and an orifice inside the valve. When the fuel cell is started, the heater is operated to prevent the frozen moisture from blocking the exhaust flow passage.